OBJECTIVES: a. To determine the effects of five hormones, two cyclic nucleotides, two classes of inducers of hepatic microsomal metabolism, and antimicrotubule and antimicrofilament agents, on selected hepatic excretory functions, and their related biosynthetic processes, in isolated hepatocytes. b. To determine the mechanisms and steps involved in linking the effector hormones and drugs to the observed responses. METHODS: a. Isolated hepatocyte suspensions and cultures prepared from adult rat liver. b. Hormones: Gastrin, secretin, cholecystokinin, glucagon, and thyroxine added to liver cells in vitro. c. Drugs: Phenobarbital, 3-methylcholanthrene, colchicine, vinblastine, cytochalasin B. d. Determinations: Bile acid synthesis, transport, and conjugation; cholesterol 7 alpha-hydroxylase. Bilirubin transport, ligandin, and bilirubin-UDPGA-transferase Microsomal P450 (hexobarbital hydroxylase, aminopyrine-N-demethylase). Microsomal P448 (benzo-a-pyrene hydroxylase). Microsomal O-aminophenol-UDPGA-transferase. Triglyceride release, cholesterol biosynthesis, HMG-CoA-reductase. Cyclic-AMP and Cyclic GMP concentrations.